You know that Quench, more correctly called Squish, is the distance between the piston and the top of the chamber, at the furthest from the sparkplug... right?
On a closed chamber head, with the pistond even with the top of the deck, then Q =gasket thickness, so it is easy to obtain and select-fit.
But when using a stock Mopar open chamber head with the pistons down in the hole, Q is impossibly huge.
On your heads, I have measured the chamber on the squish side as from .099 to .127, so if you milled to 65cc, that would be about .035 off the squish, so for arguments sake, lets say your heads started at .100. Therefore they would now be .065, right.
Now add the .012 that the pistons are down in the hole, and I wouldn't use anything but the .039 FelPro,
that adds up to ; .065 +.012 +.039=.116
Therefore, your Q is still impossibly huge to provide any benefit.
In order to get into the zone of .035 to .045, as you can see, with open-chamber heads, will require a specialty piston with a Quench-pad already on it, which you may have to adjust the height of, to work with your now shaved heads.
BTW
as to the KB107s
Between yrs 2000 and 2016, my 367 accumulated over 100,000 miles, on those,with no issues. I run a 4-speed, and the car never comes home to roost, that she hasn't been to 7000/7200 many many times. She was daily driver for many years. I have no problem recommending them, so long as the gaps are set right.
and I just gotta say this; mine also liked a skirt clearance of .0035, which I run at 205* minimum cooling temp. This is the set up that trapped 93 in the Eighth with a 230 cam. The Wallace calculator spits out 433hp at 3457 pounds and 930ft elevation. How much of that is due to the .034Q is not for me to say.
The thing is, I never built to that Q-spec for absolute power. Rather, I built it for Part-Throrrle torque and fuel economy...... because it was to be my DD, and I had heard it was worth about one cam size. In other words, I could run a 223 cam instead of a 230, and cash in on the higher cylinder pressure for hiway mpgs. And it worked.
The ugly zone for Q is said to be between .050 and .080. I have no experience with that.
